Re: My coreXY design is progressing to the build stage May 11, 2016 06:20AM |
Registered: 8 years ago Posts: 622 |
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the_digital_dentist
Yes, two-level belts. Attempting to set approximately equal tension on both belts at the same time might require me to grow and extra arm or two. It's OK- the screws will attach the belt clamps to the inside of a rectangular aluminum tube and prevent it from going anywhere. I'll countersink the holes to force the screws to center themselves in the holes.
Re: My coreXY design is progressing to the build stage May 11, 2016 07:57AM |
Registered: 12 years ago Posts: 5,796 |
Re: My coreXY design is progressing to the build stage May 11, 2016 02:08PM |
Registered: 12 years ago Posts: 1,049 |
Re: My coreXY design is progressing to the build stage May 11, 2016 02:39PM |
Registered: 12 years ago Posts: 5,796 |
Re: My coreXY design is progressing to the build stage May 12, 2016 03:26AM |
Registered: 8 years ago Posts: 622 |
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the_digital_dentist
I'll be using smooth pulleys made from F608ZZ bearings. A 40 tooth pulley is about 25 mm diameter. F608ZZs are 22 mm diameter.
That stuff from SDP/SI is a little tricky to interpret. When they say "idler" pulley they seem to be talking about things like pulleys used to adjust belt tension- idler arc of contact should be minimum? Hmmm.
I've seen other info (can't find the link) that said there should be a minimum of 6 teeth in contact with a smooth pulley. In this application, we have 90 degree contact, and since the pulleys are equivalent diameter of about a 34 tooth pulley, there will be at least 8 teeth of the belt in contact with the pulley. I think it will be OK.
Re: My coreXY design is progressing to the build stage May 12, 2016 09:46AM |
Registered: 8 years ago Posts: 776 |
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the_digital_dentist
That stuff from SDP/SI is a little tricky to interpret. When they say "idler" pulley they seem to be talking about things like pulleys used to adjust belt tension- idler arc of contact should be minimum? Hmmm.
Anonymous User
Re: My coreXY design is progressing to the build stage May 12, 2016 11:48AM |
Re: My coreXY design is progressing to the build stage May 12, 2016 12:04PM |
Registered: 12 years ago Posts: 5,796 |
Re: My coreXY design is progressing to the build stage May 12, 2016 12:55PM |
Registered: 10 years ago Posts: 344 |
Anonymous User
Re: My coreXY design is progressing to the build stage May 12, 2016 01:37PM |
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the_digital_dentist
I ordered the F608ZZ bearings for $8 for 10 pieces. Where do you get cheap toothed pulleys?
Re: My coreXY design is progressing to the build stage May 12, 2016 02:53PM |
Registered: 12 years ago Posts: 1,049 |
Re: My coreXY design is progressing to the build stage May 12, 2016 04:17PM |
Registered: 12 years ago Posts: 5,796 |
Re: My coreXY design is progressing to the build stage May 12, 2016 04:22PM |
Registered: 12 years ago Posts: 5,796 |
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gforce1
@ DD Why don't you twist the belts that are running on the outside? Then they are running with the smooth side on the idlers.
Anonymous User
Re: My coreXY design is progressing to the build stage May 12, 2016 11:02PM |
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the_digital_dentist
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gforce1
@ DD Why don't you twist the belts that are running on the outside? Then they are running with the smooth side on the idlers.
I tried that before and found it difficult to keep the belt centered on the pulley, but maybe the distance between the pulleys was too small. I may try it again with this build, but there isn't much room on that side for the twist.
Re: My coreXY design is progressing to the build stage May 13, 2016 12:21AM |
Registered: 12 years ago Posts: 5,796 |
Anonymous User
Re: My coreXY design is progressing to the build stage May 13, 2016 02:19AM |
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the_digital_dentist
I'm a lot less concerned about the appearance than the function. It's also quite easy to fabricate the brackets from aluminum tubing, requiring only a saw, drill, and a file or deburring tool for clean-up (though I'll probably mill the cuts just make it look more "professional").
Anonymous User
Re: My coreXY design is progressing to the build stage May 13, 2016 02:29AM |
Re: My coreXY design is progressing to the build stage May 13, 2016 07:50AM |
Registered: 12 years ago Posts: 5,796 |
Anonymous User
Re: My coreXY design is progressing to the build stage May 14, 2016 04:25AM |
Re: My coreXY design is progressing to the build stage May 14, 2016 07:18AM |
Registered: 12 years ago Posts: 5,796 |
Anonymous User
Re: My coreXY design is progressing to the build stage May 14, 2016 08:57AM |
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the_digital_dentist
How can you tell if the balls are but the races are not hardened with just a visual inspection?
And do the cheap, toothed pulleys you previously suggested come with "proper" bearings?
Re: My coreXY design is progressing to the build stage May 14, 2016 10:18AM |
Registered: 12 years ago Posts: 5,796 |
Anonymous User
Re: My coreXY design is progressing to the build stage May 14, 2016 10:59AM |
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the_digital_dentist
I've used HDD bearings in extruder experiments, too. They are probably the best bearings made. A little too small for 3D printer idlers unless you press them into machined pulleys. The next problem with them is the tiny screw hole...
On another topic- the motor for one of the belts will be positioned perfectly if I use a piece of the 2" square tubing for the motor mount. The other motor mount can be made using a piece of 1.5" x 2" tubing. Very simple, and very cheap. Cutting grooves in the plate to allow adjustability will be a little tricky. If I cut the plate narrower I can just make clamps that fit and then I won't have to mill narrow slots in the plate.
Re: My coreXY design is progressing to the build stage May 14, 2016 05:26PM |
Registered: 12 years ago Posts: 5,796 |
Re: My coreXY design is progressing to the build stage May 14, 2016 05:59PM |
Registered: 12 years ago Posts: 1,049 |
Anonymous User
Re: My coreXY design is progressing to the build stage May 14, 2016 09:50PM |
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the_digital_dentist
I have a box full of the little screws from the HDDs. When you need a small screw or three it's hard to find them anywhere else.
I'll probably go with the clamp.
Anonymous User
Re: My coreXY design is progressing to the build stage May 14, 2016 10:09PM |
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cozmicray
The 608, 608z, 606zz are common used skateboards
z -- designate shield on side. rs - designates sealed
Might look at ABEC rateing -- higher suppose to be better
but are not tested/ rated for reciprocating (back and forth) operation
Hey these are used for direction change, are they really loaded
Is the inner race pressed onto axle so the bearing is in proper use?
Mount it on a shaft, tight fit to shaft
spin it both directions
Does it continue to spin?
Is it noisy?
Might have to clean them out well. Kerosene, WD40.
If you clean them out well -- may have to lube them up with very light oil.
Select good ones.
Give the bad ones for the neighborhood skateboarder
but he probably has the top notch ceramic bearings?
Re: My coreXY design is progressing to the build stage May 15, 2016 06:03PM |
Registered: 8 years ago Posts: 776 |
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cozmicray
Give the bad ones for the neighborhood skateboarder
but he probably has the top notch ceramic bearings?
Re: My coreXY design is progressing to the build stage May 20, 2016 01:59AM |
Registered: 9 years ago Posts: 1,035 |
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the_digital_dentist
Cutting grooves in the plate to allow adjustability will be a little tricky. If I cut the plate narrower I can just make clamps that fit and then I won't have to mill narrow slots in the plate.
Re: My coreXY design is progressing to the build stage May 20, 2016 05:59AM |
Registered: 14 years ago Posts: 268 |